frc::TrapezoidProfile< Distance > Class Template Reference

A trapezoid-shaped velocity profile. More...

#include <frc/trajectory/TrapezoidProfile.h>

Classes
class	Constraints
	Profile constraints. More...
class	State
	Profile state. More...

Public Types
using	Distance_t = units::unit_t<Distance>
using	Velocity
using	Velocity_t = units::unit_t<Velocity>
using	Acceleration
using	Acceleration_t = units::unit_t<Acceleration>

Public Member Functions
constexpr	TrapezoidProfile (Constraints constraints)
	Constructs a TrapezoidProfile.
constexpr	TrapezoidProfile (const TrapezoidProfile &)=default
constexpr TrapezoidProfile &	operator= (const TrapezoidProfile &)=default
constexpr	TrapezoidProfile (TrapezoidProfile &&)=default
constexpr TrapezoidProfile &	operator= (TrapezoidProfile &&)=default
constexpr State	Calculate (units::second_t t, State current, State goal)
	Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.
constexpr units::second_t	TimeLeftUntil (Distance_t target) const
	Returns the time left until a target distance in the profile is reached.
constexpr units::second_t	TotalTime () const
	Returns the total time the profile takes to reach the goal.
constexpr bool	IsFinished (units::second_t t) const
	Returns true if the profile has reached the goal.

Detailed Description

template<class Distance>
class frc::TrapezoidProfile< Distance >

A trapezoid-shaped velocity profile.

While this class can be used for a profiled movement from start to finish, the intended usage is to filter a reference's dynamics based on trapezoidal velocity constraints. To compute the reference obeying this constraint, do the following.

Initialization:

TrapezoidProfile::Constraints constraints{kMaxV, kMaxA};
double previousProfiledReference = initialReference;
TrapezoidProfile profile{constraints};

Run on update:

previousProfiledReference = profile.Calculate(timeSincePreviousUpdate,
                                              previousProfiledReference,
                                              unprofiledReference);

where unprofiledReference is free to change between calls. Note that when the unprofiled reference is within the constraints, Calculate() returns the unprofiled reference unchanged.

Otherwise, a timer can be started to provide monotonic values for Calculate() and to determine when the profile has completed via IsFinished().

Member Typedef Documentation

Acceleration

template<class Distance >

using frc::TrapezoidProfile< Distance >::Acceleration

Initial value:

 
      units::compound_unit<Velocity, units::inverse<units::seconds>>

Acceleration_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Acceleration_t = units::unit_t<Acceleration>

Distance_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Distance_t = units::unit_t<Distance>

Velocity

template<class Distance >

using frc::TrapezoidProfile< Distance >::Velocity

Initial value:

 
      units::compound_unit<Distance, units::inverse<units::seconds>>

Velocity_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Velocity_t = units::unit_t<Velocity>

Constructor & Destructor Documentation

TrapezoidProfile() [1/3]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile ( Constraints constraints )

inlineconstexpr

Constructs a TrapezoidProfile.

Parameters

constraints

The constraints on the profile, like maximum velocity.

TrapezoidProfile() [2/3]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile ( const TrapezoidProfile< Distance > & )

constexprdefault

TrapezoidProfile() [3/3]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile ( TrapezoidProfile< Distance > && )

constexprdefault

Member Function Documentation

Calculate()

template<class Distance >

State frc::TrapezoidProfile< Distance >::Calculate ( units::second_t t, State current, State goal )

inlineconstexpr

Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.

Parameters

t	How long to advance from the current state toward the desired state.
current	The current state.
goal	The desired state when the profile is complete.

Returns

The position and velocity of the profile at time t.

IsFinished()

template<class Distance >

bool frc::TrapezoidProfile< Distance >::IsFinished ( units::second_t t ) const

inlineconstexpr

Returns true if the profile has reached the goal.

The profile has reached the goal if the time since the profile started has exceeded the profile's total time.

Parameters

t	The time since the beginning of the profile.

Returns

True if the profile has reached the goal.

operator=() [1/2]

template<class Distance >

TrapezoidProfile & frc::TrapezoidProfile< Distance >::operator= ( const TrapezoidProfile< Distance > & )

constexprdefault

operator=() [2/2]

template<class Distance >

TrapezoidProfile & frc::TrapezoidProfile< Distance >::operator= ( TrapezoidProfile< Distance > && )

constexprdefault

TimeLeftUntil()

template<class Distance >

units::second_t frc::TrapezoidProfile< Distance >::TimeLeftUntil ( Distance_t target ) const

inlineconstexpr

Returns the time left until a target distance in the profile is reached.

Parameters

target

The target distance.

Returns

The time left until a target distance in the profile is reached.

TotalTime()

template<class Distance >

units::second_t frc::TrapezoidProfile< Distance >::TotalTime ( ) const

inlineconstexpr

Returns the total time the profile takes to reach the goal.

Returns

The total time the profile takes to reach the goal.

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The documentation for this class was generated from the following file:

• frc/trajectory/TrapezoidProfile.h